A long time ago, when I was nothing more than a colourless clump of cells the size of a grape pip clinging to the dark inside of my mother's body, something happened to change the entire course of my life. Deep within my cells, a muffled detonation on one of my chromosomes triggered an unstoppable and irreversible chain re­action. A new genetic force pulsed through my minuscule body, throwing one cellular switch after another and resetting the co­ordinates of my embryonic voyage. Imperceptibly at first, degree by degree, I was diverted away from the normal course of develop­ment. Cells within my body laid aside one set of genetic instructions, unrolled another blueprint and set to work altering my small anatomy. Doors that had opened onto long corridors I was following were suddenly closed, and I could not turn back. Other doors opened that led me off in a different, unfamiliar direction, a direction which was eventually to set me apart from half of humanity. Seven and a half months later I was pushed out from my warm home into the blinding white light of the world. The very first words I ever heard defined what I had become. 'It's a boy.'

The corresponding announcement which greets every birth colours the entire life of every one of us from the cradle to the grave. Sex is our principal badge, the first characteristic of any sort of personal description. The fact that we humans exist in two forms is so much part of everyday life, and always has been, that we rarely pause to question why this should be. Yet, the simple dis­tinction between male and female divides our species into two perennially polarized camps separated on either side of a great canyon from whose rim we signal to each other and struggle to hear, but which we can never cross.

It is no secret that, underneath it all, men are basically genetically modified women. In this respect, our evolution can be regarded as a gigantic and long-running GM experiment. Its legacy has been to endow men and women with different and often con­flicting sets of genetic interests, and to set off a powerful evolutionary spiral which has rapidly and sometimes dangerously accentuated the differences between the two sexes. This book is my explanation, as a geneticist, of the causes and effects of this end­lessly fascinating yet often troublesome experiment which bewitches and entangles us all.

I have called the book Adam's Curse because the experiment which gave us men is not turning out too well just now, as any look at the newspapers easily confirms. Here are just two from the inside pages of today's editions.

POLICE HUNT VIOLENT LONER AFTER WOMEN ARE DISMEMBERED. A

dangerous loner believed to have killed and dismembered two women was being hunted by police last night. Scotland Yard named Anthony John Hardy, an unemployed man in his mid-fifties, who lived close to where the remains of the women were found in Camden Town, north London. {Daily Telegraph)

MURDER CHARGE. Brian McCormack, 19, appeared before magistrates in Manchester charged with the murder of Jolyon Griffin, 28, who died on Christmas Day after being attacked on a city centre bus 11 days ago as he made his way home after a night out. {The Times)

In both cases, the suspect is a man. I would have had to search the papers for weeks to find a woman accused of a comparable crime. On the same day a far more disturbing yet not entirely un­connected story dominated the front pages:

BUSH SENDS 15,000 TROOPS TO GULF AS IRAQ ATTACK NEARS. America

yesterday ordered its first full infantry division to the Gulf, prompt­ing Pentagon sources to say that an attack against Iraq could be launched at any time. {Daily Mail)

It is a weary lament to lay most acts of violence and aggression, from the strictly local to the truly global, squarely at the feet of men. Yet the association is strong and undeniable. Women only rarely commit violent crimes, become tyrants or start wars. In Adam's Curse I explore the genetic explanation for this stark truth and point an accusing finger at the only piece of DNA which men possess and women do not: the Y-chromosome. There are other vital genes which, though both sexes carry them, are passed on only by women. These differences lie at the very heart of the genetic conflict between the sexes, set up by the great experiment, which resonates throughout our daily lives. Ironically, although the Y-chromosome has become synonymous with male aggression, it is intrinsically unstable. Adam is as much cursed as cursing. Far from being vigorous and robust, this ultimate genetic symbol of male machismo is decaying at such an alarming rate that, for humans at least, the GM experiment will soon be over. Like many species before us who have lost their males, we run the real risk of extinction.

The more I dug down, the more I realized that the two sexes are caught in a dangerous genetic whirlpool, playing out in the flesh irreconcilable conflicts embedded deep within our genomes. As much by luck as judgement, my own research on DNA placed me in a unique position to observe this primal struggle. I found myself with the means to follow the different genetic histories of men and women. I could listen to the messages carried by DNA and catch the whispers of old lives passed on by generation after generation of ancestors. When I finally woke up to what they were telling me, a lot of things that had made no sense at all started to fall into place. Adam's Curse is the result.

On a very practical note, sex and the reasons for it are fundamental to this book, and I use the word in several different contexts. Sometimes it refers to reproduction, sometimes to gender and some­times to intercourse. I adopt this general usage to avoid, among other things, the angst of defining exactly what I mean by gender and to sidestep such literary absurdities as describing the shedding of pollen as any sort of intercourse. I hope the context will make my meaning clear.